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Lam Patent No. 74,329, dated February 11, 1868.

IMPROVEMENT IN DUST-CUPS roe WATCHES.

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TO ALL WHOM IT MAY CONCERN:

Be it known that I, WESLEY FENIMORE, of Philadelphia, Pennsylvania, haveinvented an Adjustable Dust- Cup for Watches; and I do herebydeclare thefollowing to be a full, elear,'and exact description of the same.

My invention relates to an improvement in the ring which is termed thedust-cup, and which usually surrounds that ortion of the arbor of awatch which ro'ects throu h the back 'late'of the works for receivin P P.l c P D the key; and my improvement consists in so constructing adust-cup that it can be readily adjusted and a tight joint effected, toprevent fine dust from gaining access through the key-hole of thecap-plate to the works of a In order to enable others'skilled in the artto make and apply my invention, I will now proceed to describe itsconstruction and operation, reference being had to the accompanyingdrawing, which forms a part of this Figure 1 represents, in sectionandonan enlarged scale, sufi'icient of a watch to illustrate my invention.Figure 2 a portion of fig. 1, detached. v i I A represents part of theback plate of a watch, between which and the front plate are confinedthe works,

and Brepresents part of the cap, that is, the plate hinged to the case,and intervening between the back of the latter and the plate A. Drepresents the outer end of one of the arbors, to which the key isusually applied for winding up the watch or for turning the pointers,the arbor having the usual square termination adapted to the hole in thekey, and turning in the plate A. v

In watches it is usual to surround the projecting portion of the arborwith a hollow cylinder, (termed the du'st-cup,) secured to the plate A,and projecting so far beyond the latter that the cap B, when closed,will bear, against the outer end of thecylinder, and thus prevent finedust from penetrating through the hole in the cup B, for admitting thekey to the spacebotween the said cap and the plate A, and to the works.

It. is rarely, however, that a perfectly dust-tight joint is obtainedbetween the outer end of the dust-cup,as

usually constructed, and the cap, as the slightest distortion of thelatter will result in a joint so imperfect as to admit fine particles ofdust to the worksa delect'which my invention is designed to obviate.

D is a ring, situated concentrically with the arbor D, and secured tothe plate A by set-screws passing through the flange a of the said ringinto the plate. On the exterior of the ring are cut screw-threads,adapted to internal threads in a ring, E, which forms the adjustabledust-cup. This ring is reduced in diameter at its outer end, so as toform an annular shoulder, e, against which bears the cap B, when thelatter is closed, the

portion thus reduced in diameter fitting snugly in an opening made forits reception in the said cap B.

It should be understood that the ringE is screwed so tightly to the ringD, that the former cannot be turned by any ordinary agitation to whichthe watch may be subjected, but yet not too tightly to prevent itsadjustment by a slight eil'ort with a suitable instrument.

It will be evident that a perfectly dust-tight joint may bemade betweenthe outer end of the ring Eand the cup 13, by a proper adjustment of theformer in respect to the latter. I prefer the reduction of the ring indiameter at the top, so as to penetrate the opening in the cap, andforni a shoulder for the latter to bear agaiii st, as by thisarrapgemcnt there are two joints to bar the entrance of the dust. A veryeffective dust-tight joint may, however, be made, without causing thering E to penetrate the cap 13, the latter bearing against the end onlyof a plain ring, which admits of such delicate adjustment that thedesired joint maybe easily obtained.

I claim as my invention, and desire to secure by Letters Patentv it 1; Aring, E, rendered adjustable on the ringDof the plate A, in respect tothe capB of a watch, substantially as and for the purpose herein setforth.

2.- The ring E, reduced in diameter, so as to penetrate and fit snuglyin the opcningof the cap B, and having a shouldcr fer the said cap tobcar against, all as sct forth.

In testimonywberccf, Ihave signed my name to this specification in thepresence of two subscribing witnesses.

WESLEY FENIMOREL.

Witnesses;

II. l-Iowson, Cnanmas B. Paton.

